demo_app/server/src/main/java/com/example/demo/model/Message.java
<filename>demo_app/server/src/main/java/com/example/demo/model/Message.javapackage com.example.demo.model;

import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;

@Data
@Entity
@RequiredArgsConstructor
@NoArgsConstructor
public class Message {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @NonNull
    @Column(nullable = false)
    private String content;
}
